Could I be pregnant?

Sorry for being so vague, but I couldn't think of another way to be clear and concise. Here is my concern: I have just started taking birth control (Cryselle) and became sexually active again around week 2 of taking the medication. I have been punctual with taking the medication, and also been using condoms during intercourse. Now I'm on my fourth week of taking it, and my period is missing. I've never been regular and the month prior to taking Cryselle, I missed it entirely. Since this fourth week came around, I have been feeling fatigued abd experiencing breast tenderness. Is any of this normal or could I be pregnant?